This present invention relates generally to signal transmission cable structures for electronic devices and particularly to improving the performance and construction of such a cable structure by improving the ground termination at the connector of the cable structure.
The use of electronic devices of all kinds has increased dramatically throughout society, which has led to a significant increase in the demand for improved components utilized with such devices. One facet in the utilization of such electronic devices involves the data communications between such devices within a networked system. For example, many electronic devices may now be coupled and synchronized with other electronic devices, such as a computer, for transmitting data and other information back and forth between the various devices.
For accurate data and information transmission in such a system, the components of the system devices, and particularly the interface components of the system which connect between the various electronic devices, must be optimized for greater speed and performance. One particularly important interface component is the transmission cable which extends between the electronic devices that are communicating. Various cable designs have been utilized for such data and information transmission. Generally, suitable cable structures utilize a plurality of electrical conductors and a connector structure at one or both ends which interfaces with the connector structure of the electronic device. For example, connectors of a cable might plug into appropriate socket structures in the electronic devices. The electrical conductors include signal conductors; that is, transmission lines which carry the actual data or information signals, and ground conductors which provide an electrical reference for the transmitted data and information.
While the conductor or cable portions of existing cable structures have been suitable in maintaining the integrity of the signals transmitted thereon, significant attention has been paid to the termination components of the cable structure, generally referred to as the connector. The connector of the cable structure provides a transition between the individual electrical conductors of the cable portion, and hence the transmitted signals, and the internal circuitry of the electronic device to which the cable structure is connected. Generally, such connectors utilize a plurality of contacts, often in the form of conductive strips, pins and/or tabs. The electrical conductors, i.e., the signal and ground conductors, terminate at the contacts of the connector, and are electrically coupled to the contacts. The electronic device then includes its own set of contacts, such as pins or tabs, within a socket, for example, for interfacing with the contacts of the connector and thereby providing electrical coupling between the electronic devices at either end of the cable structure. Oftentimes, the interface between a cable structure connector and electronic device involves the cable structure connector engaging a socket in the electronic device, which includes pins or other contacts that engage the connector in a male-female relationship. However, Various other different connector structures have been utilized as evidenced by numerous patents in the field directed to such connector designs.
In some cable structures, each signal conductor is associated with a ground conductor. Therefore, the connectors of such cable structures provide individual contacts for each of the signal conductors and each of the ground conductors. Therefore, there are multiple ground contacts in the connectors. However, depending upon the number of conductors within a cable structure, such an arrangement may require a large or bulky connector structure. It is a goal within the field of transmission cable structures to minimize the size of the connector, while still maintaining a sufficient signal conductor density and maintaining the integrity of the transmitted signals.
To that end, attempts have been made to make cable structures wherein the connectors utilize multiple ground conductors which are electrically coupled to a single ground reference. Since the ground conductors are not carrying different signals, they can all be coupled to a suitable single ground reference without affecting the operation of the cable structure. For example, some attempts have been made to couple all the ground connectors to a grounding shield. Another cable structure utilizes a grounding device including a carrier strip with a plurality of conductive strips extending therefrom. The conductive strips are coupled to the carrier strip by score lines and thus may be readily separated from the carrier strip. Depending upon the connector design, one or more conductive strips will be utilized with the carrier strip to make the ground connection within the connector, whereas other conductive strips are broken off from the carrier strip at their score lines to form signal contacts. The carrier strip is then connected to the ground conductors and one or more of the conductive strips still connected to the carrier strip form the ground contact of the cable structure. A single ground reference is thus utilized to service various of the ground conductors. Other of the conductive strips form the signal contacts.
While the goal of utilizing a single ground reference for multiple ground conductors within a cable structure is achieved, prior designs have had significant drawbacks. First, such designs are generally less robust due to the score lines between the conductive-ground contacts and carrier strip. Movement of the cable and manipulation of the connector may cause physical separation of the ground strips at the score line, thus creating an open circuit condition at the ground contacts. Furthermore, during the manufacturing of a cable structure utilizing such a connector design, an additional and costly step is involved to detach any non-ground contacts from the carrier strip and to insure that the grounded carrier strip is only coupled to the ground contacts and not any of the signal contacts.
Another drawback to such a design is the tenuous signal integrity that exists in such a connector. The contact/carrier strip design requires very close proximity of the grounded carrier strip and the signal contact strips which have been detached from the carrier strip. Thus, movement of the contact strips or the carrier strip may result in shorting of the signal conductor to ground. Accordingly, prior art structures utilizing such a connector-ground configuration have a less robust construction wherein signal integrity is jeopardized and additional manufacturing steps are required, thus increasing the cost of manufacturing the cable structure.
Still another drawback to existing connector designs involves the conductor cross-over that is often utilized in such designs. Specifically, the signal conductors may cross over the ground conductors for construction of the connector. In further constructing the connector, it may be necessary to apply pressure and or high temperatures to the end of the cable, such as when the connector body is being molded around the ends of the conductors. When the conductors are crossed over each other, they may be pressed together under the high temperature and pressure and this may cause a short circuit condition.
Therefore, it is desirable to have a cable structure for communication between electronic devices which has improved signal integrity through the connector.
Furthermore, it is desirable to reduce the cost of manufacturing such cable structures and connectors.
Additionally, it is desirable to reduce the possibility of shorting between a signal conductor and a ground conductor within the connector to thereby further improve the integrity of the signal transmitted through the cable structure.
It is further desirable to have a connector design which is sufficiently compact, but which maintains a useful density of signal conductors.
These objectives and other objectives will become more readily apparent from the summary of invention and detailed description of embodiments of the invention set forth herein below.
The cable structure of the invention maintains the signal conductors and ground conductors within separate, spaced planes to improve the signal integrity of the cable structure and reduce the possibility of the signal conductors shorting to ground. The ground contact is maintained in a common plane with the other signal contacts to thus keep the size of the connector structure suitably compact.
In one embodiment of the invention, a shorting bar has a first portion which is positioned generally within a contact plane defined by and containing other signal contacts. A second portion of the shorting bar is positioned in a second or ground plane which is vertically spaced from the contact plane, and is electrically coupled to various ground conductors. In the embodiment of the invention illustrated, the shorting bar is coupled to the ground conductors in a ground plane rearward of and vertically below the contact plane containing the signal conductors. Thus, signal integrity and the durability of the cable is improved, and the need for conductor cross-over is eliminated.
In one embodiment of the invention, a connector housing has a plurality of housing contacts positioned therein which define a contact plane. The contacts are configured for interfacing with pins of a socket in the electronic device to which the cable structure is connected. One or more signal conductors terminate in the connector housing and the terminal ends of the signal conductors are electrically coupled to the housing contact, generally within the contact plane. In one embodiment of the invention, the contacts have flat strip portions and the terminal ends of the signal conductors are positioned on top of the strip portions and welded thereto.
One or more ground conductors are positioned alongside the signal conductors and terminate in the connector housing. The electrically conductive shorting bar has a first portion which is positioned proximate and generally within the contact plane and which is electrically coupled to one of the housing contacts to thereby form and define the ground contact. A second portion of the shorting bar, including multiple legs, is positioned generally in the second, or ground, plane which is vertically spaced from the first portion. The second portion is welded to the terminal ends of the ground conductors. Therefore, the terminal ends of the ground conductors are maintained in a plane vertically spaced from the contact plane in which the signal conductors terminate.
In a preferred embodiment, the shorting bar couples to the terminal ends of the ground conductors, not only in a plane below the contact plane containing the terminal ends of the signal conductors, but also longitudinally rearwardly of the signal conductor terminal ends. The shorting bar thus maintains the signal conductor and ground conductor terminations within separate, spaced planes to improve the signal integrity of the cable structure and reduce the possibility of the signal conductor being grounded.
However, the shorting bar is also coupled to housing contacts within the contact plane such that all the housing contacts are maintained within a common plane to keep the size of the connector suitably compact. Furthermore, the conductors are maintained in a side-by-side fashion at the ends thereof without any cross-over of the conductors. This further reduces the possibility of an undesired short circuit at the connector.
In one embodiment of the invention, the shorting bar is in the form of a unitary metal strip which includes a transition portion spanning between the first and second portions. The first, second, and transition portions are all integrally formed of an electrically-conductive material such as metal, and the second section comprises a plurality of legs which extend laterally with respect to the longitudinal axis of the first portion of the shorting bar to engage the ground conductors where they terminate, rather than having the ground conductors bend significantly toward the center ground contact and create a cross-over situation.
The cable structure further comprises a shield including a tab depending downwardly therefrom and electrically coupled to the ground contact and thereby electrically coupled to the grounding bar and ground conductors.
The integral construction of the shorting bar ensures that it is generally free of score lines between the first and second portions and thus provides a more robust connector. Therefore, there is little probability that a break would occur along the shorting bar thus disconnecting the ground conductors from the ground contact of the connector. Once the shorting bar is installed and welded to the ground contact and the ground conductors, there is no additional step required for further manipulating the shorting bar or other connector components to eliminate short circuits. Therefore, the cost of manufacturing the cable structure is reduced. Furthermore, since the signal conductors and ground conductors are maintained in separate, vertically-spaced planes with no cross-over, there is very little possibility of inadvertent connection between a signal conductor and a ground conductor or ground contact, to thereby improve the integrity of the signal transmitted through the cable structure. The connector is compact, and maintains a suitable density of signal conductors accessible through the connector, with a single ground contact serving as the ground reference for all the signal conductors.